From 0eeca28300df110bd6ed54b31193c83b87921443 Mon Sep 17 00:00:00 2001 From: Robert Love Date: Tue, 12 Jul 2005 17:06:03 -0400 Subject: [PATCH] inotify inotify is intended to correct the deficiencies of dnotify, particularly its inability to scale and its terrible user interface: * dnotify requires the opening of one fd per each directory that you intend to watch. This quickly results in too many open files and pins removable media, preventing unmount. * dnotify is directory-based. You only learn about changes to directories. Sure, a change to a file in a directory affects the directory, but you are then forced to keep a cache of stat structures. * dnotify's interface to user-space is awful. Signals? inotify provides a more usable, simple, powerful solution to file change notification: * inotify's interface is a system call that returns a fd, not SIGIO. You get a single fd, which is select()-able. * inotify has an event that says "the filesystem that the item you were watching is on was unmounted." * inotify can watch directories or files. Inotify is currently used by Beagle (a desktop search infrastructure), Gamin (a FAM replacement), and other projects. See Documentation/filesystems/inotify.txt. Signed-off-by: Robert Love Cc: John McCutchan Cc: Christoph Hellwig Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/inotify.h | 108 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 108 insertions(+) create mode 100644 include/linux/inotify.h (limited to 'include/linux/inotify.h') diff --git a/include/linux/inotify.h b/include/linux/inotify.h new file mode 100644 index 000000000000..a40c2bf0408e --- /dev/null +++ b/include/linux/inotify.h @@ -0,0 +1,108 @@ +/* + * Inode based directory notification for Linux + * + * Copyright (C) 2005 John McCutchan + */ + +#ifndef _LINUX_INOTIFY_H +#define _LINUX_INOTIFY_H + +#include + +/* + * struct inotify_event - structure read from the inotify device for each event + * + * When you are watching a directory, you will receive the filename for events + * such as IN_CREATE, IN_DELETE, IN_OPEN, IN_CLOSE, ..., relative to the wd. + */ +struct inotify_event { + __s32 wd; /* watch descriptor */ + __u32 mask; /* watch mask */ + __u32 cookie; /* cookie to synchronize two events */ + __u32 len; /* length (including nulls) of name */ + char name[0]; /* stub for possible name */ +}; + +/* the following are legal, implemented events that user-space can watch for */ +#define IN_ACCESS 0x00000001 /* File was accessed */ +#define IN_MODIFY 0x00000002 /* File was modified */ +#define IN_ATTRIB 0x00000004 /* Metadata changed */ +#define IN_CLOSE_WRITE 0x00000008 /* Writtable file was closed */ +#define IN_CLOSE_NOWRITE 0x00000010 /* Unwrittable file closed */ +#define IN_OPEN 0x00000020 /* File was opened */ +#define IN_MOVED_FROM 0x00000040 /* File was moved from X */ +#define IN_MOVED_TO 0x00000080 /* File was moved to Y */ +#define IN_CREATE 0x00000100 /* Subfile was created */ +#define IN_DELETE 0x00000200 /* Subfile was deleted */ +#define IN_DELETE_SELF 0x00000400 /* Self was deleted */ + +/* the following are legal events. they are sent as needed to any watch */ +#define IN_UNMOUNT 0x00002000 /* Backing fs was unmounted */ +#define IN_Q_OVERFLOW 0x00004000 /* Event queued overflowed */ +#define IN_IGNORED 0x00008000 /* File was ignored */ + +/* helper events */ +#define IN_CLOSE (IN_CLOSE_WRITE | IN_CLOSE_NOWRITE) /* close */ +#define IN_MOVE (IN_MOVED_FROM | IN_MOVED_TO) /* moves */ + +/* special flags */ +#define IN_ISDIR 0x40000000 /* event occurred against dir */ +#define IN_ONESHOT 0x80000000 /* only send event once */ + +/* + * All of the events - we build the list by hand so that we can add flags in + * the future and not break backward compatibility. Apps will get only the + * events that they originally wanted. Be sure to add new events here! + */ +#define IN_ALL_EVENTS (IN_ACCESS | IN_MODIFY | IN_ATTRIB | IN_CLOSE_WRITE | \ + IN_CLOSE_NOWRITE | IN_OPEN | IN_MOVED_FROM | \ + IN_MOVED_TO | IN_DELETE | IN_CREATE | IN_DELETE_SELF) + +#ifdef __KERNEL__ + +#include +#include +#include + +#ifdef CONFIG_INOTIFY + +extern void inotify_inode_queue_event(struct inode *, __u32, __u32, + const char *); +extern void inotify_dentry_parent_queue_event(struct dentry *, __u32, __u32, + const char *); +extern void inotify_unmount_inodes(struct list_head *); +extern void inotify_inode_is_dead(struct inode *); +extern u32 inotify_get_cookie(void); + +#else + +static inline void inotify_inode_queue_event(struct inode *inode, + __u32 mask, __u32 cookie, + const char *filename) +{ +} + +static inline void inotify_dentry_parent_queue_event(struct dentry *dentry, + __u32 mask, __u32 cookie, + const char *filename) +{ +} + +static inline void inotify_unmount_inodes(struct list_head *list) +{ +} + +static inline void inotify_inode_is_dead(struct inode *inode) +{ +} + +static inline u32 inotify_get_cookie(void) +{ + return 0; +} + +#endif /* CONFIG_INOTIFY */ + +#endif /* __KERNEL __ */ + +#endif /* _LINUX_INOTIFY_H */ -- cgit